Sprint Car Steering
To assist Sprint Car drivers wrestle the overpowered beasts around the track a typical Sprint Car Steering setup utilizes a power steering unit. Power steering units not only assist with steering, but also help reduce kick-back through the steering wheel. The most popular power steering gear is the Gen2 by KSE Racing Products.
In a Sprint Car the complete power steering unit is mounted in front of the driver’s knees in the cockpit. The steering wheel attaches directly to the power steering unit via a quick release hub. The shaft of the unit extends out the left side of the car, where the pitman arm attaches to the splined end of the shaft. A drag link is attached to the pitman arm, with the other end of the drag link attaching to what is known as the “combo arm”. The combo arm is bolted to the left front spindle. A tie rod also attaches to the combo arm, this links the left spindle to another arm on the right spindle, connecting the left and right wheels.
The Power Steering Unit
Power steering units, or power steering boxes, began to appear on Sprint Cars back in the mid to late 1970's. As with most components on a Sprint Car the weight of the power steering unit is kept to a minimum. Most units are inboard mounted, meaning the shaft of the unit only extends to the left side of the car. In older units the tube would extend the full width of the car. Inboard mounted units not only save weight, but also stop the unit stiffening the chassis. Older units also had a habit of twisting in the chassis, inboard mounting resolves this. The power steering fluid reservoir is incorporated into the live tube of the gear whereas older units required a separate reservoir. This design eliminates turbulence, aeration, and provides the most efficient cooling. Another recent development is the inclusion of wing slider ports. Wing slider rams, that allow the driver to adjust the position of the top wing, are powered by the power steering unit, the ports allow for simple attachment. During engine warm-up you may notice some drivers turning the steering wheel of their car while testing the wing slider. This is because when the engine is idling there is not enough flow in the system to operate the wing ram. By turning the steering wheel the pressure within the the system is increased, allowing the wing ram to operate correctly.
Power Steering Pump
The power steering pump is usually located on the driver’s side of the firewall. Providing the power to the Sprint Car Steering system, the pump bolts through the rear motor plate and is driven by the engine’s camshaft. The fuel pump is often attached to the power steering pump. Popular manufacturers of power steering pumps are KSE Racing Products, GME, Sweet Manufacturing & KRC Power Steering.
At 15"-17" in diameter the steering wheel of a Sprint Car is much larger than your average road car. The larger wheel, together with the power steering unit, allows the driver to turn the car with minimal input. You won't ever see a Sprint Car driver crossing over their hands while on the track, if you do they are in real trouble! Extremely light, Sprint Car steering wheels are usually made of aluminium or steel.
As mentioned previously the pitman arm attaches to the splined shaft of the power steering unit. The arms are made from aluminium alloy and are available in lengths of 12"-15". Most pitman arms have two or more holes for the drag link, this allows the effective length of the arm to be increased. Lengthening the arm quickens the sprint car Steering ratio.
Made from aluminium, chromoly or steel tubing, the drag link connects the pitman arm to the left front steering arm. When referring to drag links you may hear the the term "swaged" used. This simply means the outside diameter of the tube reduces at the ends to allow for the 5/8" internal threads. To assist with adjustment of the drag link one end of the drag link has a left hand thread and the other right. Drag links are usually made in lengths of 45"-52". Most controlling bodies require a safety strap be used on the drag link to stop injury if it breaks lose. Drag links should always be replace if bent.
The tie rod is the same as the drag link except it runs parallel to the front axle and joins the left and front wheels via the steering arms.
The Sprint Car Steering combo arm bolts to the left spindle, providing the point where the drag link connects to the left wheel. The tie rod also attaches to the combo arm, with the other end of the tie rod bolting to the right steering arm, which is bolted to the right spindle.